Plasticizers are commonly formulated into polyvinyl chloride (PVC) in order to transform rigid PVC resin into processable flexible PVC articles. Esters of phthalic acid (phthalates) are used as primary plasticizers that are incorporated at about 10-60 parts per hundred into PVC resin (phr). Epoxidized vegetable oils, such as epoxidized soybean oil (ESBO), are used as secondary plasticizers for PVC. ESBO can only be added to the PVC formulations in small amounts as its high molecular weight leads to incompatibility with PVC and unacceptably high migration of the plasticizer out of the PVC matrix. This behavior does not allow epoxidized vegetable oil to be used as a primary plasticizer for PVC. For example, ESBO cannot be added at loadings greater than about 7-10 phr. As such, the incorporation of an additional, more PVC-compatible bio-based plasticizer with the ESBO is generally desirable.
Bio-based plasticizers derived from fatty acids that contain epoxy functional groups are known in the art, as referred to hereinbelow.
U.S. Pat. No. 2,559,177 relates to plasticized polyvinyl resin compositions.
U.S. Pat. No. 2,895,966 describes plasticizer stabilizers for synthetic resins and compositions comprising said plasticizer stabilizers.
U.S. Pat. No. 3,049,504 relates to plasticizer stabilizers for synthetic resins.
U.S. Pat. No. 4,486,561 refers to improved injection moldability of polyethylene terephthalates which is achieved by the addition of an epoxidized plasticizer and a nucleating agent cooperative with the epoxidized plasticizer to achieve the improved moldability even when the composition is injection molded using mold temperatures of at least as low as 93° C.
U.S. Pat. No. 4,574,103 discloses a laminate comprising fused adherent layers of plastisol vinyl chloride polymer resins in which a first layer contains Sb2O3 and a second layer contains TiO2. The flexible laminate is useful as a roofing membrane for the roof of a building wherein the layer containing the Sb2O3 is adjacent a structural or insulation member of the roof of the building while the TiO2 layer can be exposed to the elements and can protect the Sb2O3 layer from sunlight.
U.S. Pat. No. 4,603,074 describes a compounded and plasticized vinyl chloride polymer layer, optionally supported such as with a fabric, contains an outer adherent and stain resistant layer having durability and flexibility comprising the cross-linked reaction product of a reactive polyester having free carboxylic acid groups and an alkylated benzoguanamine-, urea- or melamine-foimaldehyde resin. The vinyl chloride layer may be printed or embossed or both printed and embossed, optionally printed again, before the outer layer is applied.
U.S. Pat. No. 6,326,518 relates to halogen-containing polymer compositions comprising a latent mercaptan-containing heat stabilizer composition substantially free from the offensive odor typically associated with mercaptans are protected during processing by the degradation products of the latent (i.e., blocked) mercaptan which include a free mercaptan.
U.S. Pat. No. 6,797,753 discloses compositions and methods for plasticizing polyvinyl chloride polymers where the plasticizers contain fatty acids derived from vegetable oils and the fatty acids are substantially fully esterified with an alcohol (mono-ol or polyol), the fatty acids having unsaturated bonds that are substantially fully epoxidized, and wherein the fatty acids are added substantially randomly to one or more hydroxyl sites on the alcohol. The plasticizers may be added in amounts between about 10 to 230 phr of PVC resin.
WO2009102592 describes unhindered polyols used to react with an epoxidized soyate to make epoxidized soyate diester in the presence of a catalyst. The unhindered polyol can be 1,3-propanediol or any polyol having four or more carbon atoms with no two adjacent carbon atoms having hydroxyl functionality. A combination of catalysts is used to promote the transesterification reaction of the epoxidized soyate with the unhindered polyol to yield a high percentage of epoxidized soyate diester with epoxy functionality retained. The primary catalyst is a metallic hydroxide, and the secondary catalyst is a titanate. Bioderived epoxidized soyate diester plasticizers useful for thermoplastics and thermosets result.
Diesters of epoxidized fatty acids and epoxidized diglyceride acetates may show good plasticization and compatibility properties in PVC. However, despite their high epoxy content at high loadings, their incorporation into PVC formulations resulted in significantly reduced initial color-hold and mid-term heat stability of flexible PVC compounds.
U.S. Patent Application Publication No. 2010/0010126 and 2010/0010127 refer to the interesterification reaction between vegetal or animal oils as monoacid esters (preferentially with 1 to 12 carbons) and monoalcohol esters (preferentially with 1 to 12 carbons). The use of ethyl acetate is preferred as it is a product that may be obtained from ethanol (renewable) and has a boiling point (77° C.), which facilitates separation by vacuum distillation at the end of the reaction and its reuse. By varying the molar ratio between glycerol triester (oil or fat) and monoalcohol ester, different proportions of glycerol esters are obtained with 1 or 2 linked fatty acids and 1 or 2 linked acids of short chain, along with the formation of fatty acid ester and monoalcohol ester. After the distillation of excess residual ethyl acetate, products are obtained with viscosity from 21 to 33 cPs at 25° C., in the case of the reaction with soy oil.
Plasticizers based on acetylated fatty acids are known in the art. German Publication No. DE 4433958 teaches ring-opening products (I) of epoxidized fats, in which the free OH groups are converted into Zerevitinov-inactive forms by reaction with monofunctional carboxylic acids or functional derivatives thereof, -halides or esters of carbonic acid, -aldehydes or -ketones. Also claimed is a process for the production of (I) in which esterification is carried out by reaction with acetic acid and acetic anhydride in a multi-tray esterification column.
U.S. Pat. No. 5,075,046 describes vicinally diacyloxy-substituted compounds of the formulae (Ia), (Ib), Ic and (Id); R1[vic. (O—CO—R2)2]—H (Ia); R3[vic. (O—CO—R2)2]—CO—OR4 (Ib); R3[vic. (O—CO—R2)2]—CO—OR5[vic. (O—CO—R2)2] (Ic); R6—CO—OR5[vic. (O—CO—R2)2] (Id), in which R1 is a trivalent saturated C6-22 hydrocarbon radical, R2 is a C1-3 alkyl radical, R3 is a trivalent saturated C10-21 hydrocarbon radical, R4 is a C1-22 alkyl radical, R5 is a trivalent saturated C16-22 hydrocarbon radical, and R6 is a C1-21 alkyl radical, are prepared from the corresponding epoxidized compounds by reaction with C2-4 carboxylic anhydrides at elevated temperature in the presence of catalytic quantities of carboxylic acids corresponding to the anhydrides and/or catalytic quantities of sulfuric acid.
U.S. Pat. Nos. 6,734,241 and 6,949,597 provide a composition comprising i) a thermoplastic polymer, ii) a compound having formula (I) wherein R1, R2 and R3 are independently selected from an acyl group or a hydrogen atom, wherein at least one of R1, R2 and R3 is an acyl group (a short acyl group) having from 2 to 6 carbon atoms, wherein at least one of R1, R2 and R3 is a branched chain acyl group (a long acyl group) consisting of a saturated chain having 10 to 20 carbon atoms and a hydrophilic branch group.
U.S. Patent Application Publication No. 2004/0106812 describes an improved method for producing epoxidated glyceride acetates. The inventive method involves transesterifying epoxy fatty acid esters with triacetin.
PCT Publication No. WO 2009138508 relates to a method for preparing a composition containing at least one fatty acid ester, characterized in that the method comprises reacting a compound or a mixture of compounds having formula (II) with a carboxylic anhydride having formula (III) in the presence of a catalyst, said catalyst being selected from the group comprising the following catalysts: homogenous or heterogeneous quaternary ammoniums, heterogeneous acids, homogenous or heterogeneous bases, and mixtures thereof.
Notwithstanding the above literature, the need remains for improved bio-based compositions suitable for use as plasticizers in halogen-containing polymers, such as polyvinyl chloride (PVC) polymers, among other uses, as well as processes for the production of such bio-based compositions.